1. Field of the Invention
This disclosure generally relates to a gas supplying device for semiconductor manufacturing equipment, and more specifically, to a gas supplying device for semiconductor manufacturing equipment having an interlock apparatus for generating an interlock signal when an abnormality occurs by sensing the open/shut states of solenoid valves and opening/shutting a channel of the gas supplying device.
2. Description of the Related Art
Among semiconductor device manufacturing equipment, CVD (Chemical Vapor Deposition) equipment is used to grow a variety of films. A CVD method is mainly used to form a thin film or an epitaxial layer on a semiconductor substrate by chemical reactions after dissolving gaseous compounds. Given that a process of forming the thin film is performed by supplying gas to a reaction chamber, a CVD process is differentiated from other semiconductor device manufacturing processes.
A useful CVD reaction occurs in a wide range of temperatures (approximately 100° C.˜1200° C.), and plasma energy obtained by heat and RF (Radio Frequency) power, or optical energy from lasers or ultraviolet rays are used to dissolve the supplied gas. Also aiding the CVD process, the semiconductor substrate may be heated to accelerate reactions of a dissolved atom or a molecule and to control physical properties of the formed thin film.
However, when forming a thin film using the CVD method, it is common to supply more than two gases to the reaction chamber. For instance, in a process for forming a high-temperature oxide film, nitrious oxide (N2O) gas and silane (SiH4) gas are supplied to the reaction chamber. In a process for forming a silicon nitride film, ammonia gas (NH3) and dichlorosilane (SiCI2H2) gas are supplied. And, in a process for forming a polycrystalline silicon film doped with impurities, a source gas containing impurity ions and a silicon source gas such as silane or disilane (Si2H6) gas are supplied to the reaction chamber, thereby depositing the desired thin film.
FIG. 1 is a block diagram that roughly illustrates a configuration for a conventional gas supplying device used in the CVD equipment described above. As shown in FIG. 1, different gases (gas 1, gas 2) are supplied through each corresponding line from first and second gas sources 1, 3. Channels for gas1 and gas2 are opened/shut by interrupting a first, second, third, and fourth solenoid valves 5,7,9,11, and the amount of gas delivered to the process chamber 17a of semiconductor manufacturing equipment 17 is controlled by first and second mass flow controllers 13,15.
A main controller 19 controls the semiconductor manufacturing equipment 17 where a chemical process is performed, and outputs an electrical signal that instructs driver 21 to open or shut the first through fourth solenoid valves 5, 7, 9, 11.
The driver 21 receives the electrical signal from the main controller 19, and controls the solenoid valves 5, 7, 9, 11. That is, when receiving the electrical signal from the main controller 19, a predetermined voltage is applied to the solenoid valves 5, 7, 9, 11 from a power supplying unit (not shown) of the driver 21 to operate the solenoid valves 5, 7, 9, 11, thereby opening or shutting the channels.
In FIG. 1, signal lines where an electrical signal is transmitted are displayed as solid lines, gas supplying lines are displayed as dotted lines, and input/output lines that apply the driving voltage to the solenoid valves 5, 7, 9, 11 are labeled ‘In’ and ‘Out’.
According to the conventional art, when the driving voltages are not properly applied to the solenoid valves 5, 7, 9, 11, the driving states of the solenoid valves become abnormal, possible causing a malfunction of the valves.
For example, suppose that the first and the third solenoid valves 5, 9 maintain a closed state (indicated by “C”) during normal operation, and the second and the fourth valves 7, 11 maintain an open state (indicated by “O”) during normal operation. The situation where gas 1 is supplied at a higher pressure than gas 2 is described below and illustrates how problems may occur.
First, if the first or the third solenoid valve 5, 9 becomes abnormal because it does not maintain a perfectly closed state, causing the channels to be opened, the unwanted gas 1 can be supplied to the process chamber 17a of the semiconductor manufacturing equipment 17, thereby generating an unwanted process film on a processing substrate located inside the semiconductor manufacturing equipment 17. In addition, if gas 1 has a higher pressure than gas 2, and if the solenoid valve 5 or solenoid valve 9 does not maintain a closed state, there is a possibility that gas 1 will flow backward into the lines where gas 2 is supplied (thick dotted lines).
Embodiments of the invention address these and other disadvantages of the prior art.